1. March 2, 2006 3D Mesh Coding and Transmission Lihang Ying Department of Computing Science University of Alberta

2. L.Ying, 3D Mesh Coding and Transmission, 2006. 2 Outline  3D Mesh Data  3D Mesh Coding –Valence-Driven Approach  Error-Resilient 3D Mesh Coding and Transmission –Multiple Description Coding  Proposed Research

3. L.Ying, 3D Mesh Coding and Transmission, 2006. 3 3D Mesh Data  Geometry: –3D positions (x-y-z coordinates) of vertices –Coding: 1)Quantization, 2)Differential Coding, 3) Entropy Coding  Connectivity: –How vertices are connected Raw data: vertex indices of each face Large redundancy –Main Focus of 3D Mesh Coding  Photometry –Colors,Normals,Texture

4. L.Ying, 3D Mesh Coding and Transmission, 2006. 4 3D Mesh Coding  Since early 1990s  Up-to-date Survey: [PKK05] VRML V.2 and MPEG-4 Standard State-of-the-art Method

5. L.Ying, 3D Mesh Coding and Transmission, 2006. 5 Valence-Driven Approach  Encoding  Thick line: active lists  Dashed line: visited edge  Dark point: focus  Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4 add 6, add 7, add 4add 4add 8 add 5 add 4 add 5 split 5add 4 add dummy 6 add 4

6. L.Ying, 3D Mesh Coding and Transmission, 2006. 6 Valence-Driven Approach  Decoding  Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4  Thick line: active lists  Dashed line: visited edge  Dark point: focus add 6, add 7, add 4add 4add 8add 5 add 4add 5 split 5 add 4 add dummy 6 add 4

7. L.Ying, 3D Mesh Coding and Transmission, 2006. 7 Progressive Valence-Driven 3D Mesh Coding –

8. L.Ying, 3D Mesh Coding and Transmission, 2006. 8 Connectivity Coding is Sensitive to Error –Previous codes impact all subsequent codes. –Example: one-code error in Edgebreaker method [Rossignac99] results (the right):

9. L.Ying, 3D Mesh Coding and Transmission, 2006. 9 Error Resilience  Error-Resilient Transmission [AAR05] –Unequal Error Protection –Interleaved Packets  Piece-based Error-Resilient Coding [YKK01] –Divide mesh into pieces, encode piece by piece, then encode connectivity between pieces.

10. L.Ying, 3D Mesh Coding and Transmission, 2006. 10  Progressive Coding –Enhance layers depends on base layers  Piece-based Error-Resilient Coding –Not friendly to Perceptual Quality  Multiple Description Coding –Each description can be encoded independently –More descriptions received result higher quality. –Less efficient Multiple Description Coding(1)

11. L.Ying, 3D Mesh Coding and Transmission, 2006. 11 Multiple Description Coding(2)  Existing Work [JWC04] –Idea: Only split the geometry (vertex position) data into descriptions Transmit the connectivity of the entire mesh via a high quality channel. –How to split vertices into descriptions Should be spaced evenly in the mesh for interpolating missed vertices Construct a vertex spanning tree and assign each vertex at level l into i -th description.

12. L.Ying, 3D Mesh Coding and Transmission, 2006. 12 Multiple Description Coding(3)  Existing Work [JWC04]

13. L.Ying, 3D Mesh Coding and Transmission, 2006. 13 Proposed Research  Objective –With packet loss: wireless network –No retransmission: real-time applications –No error protection –Perceptual quality friendly  Multiple Description Connectivity Coding

14. L.Ying, 3D Mesh Coding and Transmission, 2006. 14 Will Improve on Valence- Driven Approach  With trivial size and be kept in all descriptions  Or, can be interpolated add 6, add 7, add 4add 4add 8add 5 add 4add 5 split 5 add 4 add dummy 6 add 4

15. L.Ying, 3D Mesh Coding and Transmission, 2006. 15 The End Thank you!